Threadless
http://www.threadless.com
How’s this for interactive wear?
Threadless is an “ongoing T-shirt design competition.” Users submit their own T-shirt designs to the site, where they get to be voted on by other users for a period of seven days.
After that, designs with the highest scores get to be printed and sold on the site, and users who win receive up to $1000 in cash & prizes.
The site’s full catalog consists of over 150 designs. It also features a photo gallery of users wearing these shirts, as well as interviews of some of the designers.